You state your pH is 7? If that is the case, it is too high and causing nute lock. You need to be more precise with your pH readings as that is the key for your plant absorbing nutrients. You need to keep your range between 6.3 and 6.8, with optimal being 6.5

I have included a chart so you can see what is being locked out if indeed your pH is 7

GTD
GreenThumbDoc Reviewed by GreenThumbDoc on . Quick yellowing in advanced flowering. Plz help Hi all, tanks for having me, first grow, first post ;) Before we get into business i would like to anticipate tat i ave done my thorough researces about the issue at hand and found many similar problems, similar, but not same, and would like some reassurance. For starters the system: 1 400 W HPS with full ventilation 15 l pots (that's like 4 gallons to you yankees :)) All mix soil (bought from growing store) Temp and hum: 76.8 Average, 40% Stable Rating: 5